R1 + R2 Lamps removed?

[Ross1]

Hi, does anyone remove lamps when testing R1 + R2 as it says in OSG & GN3.

I`m only getting a 0.02 ohm difference on a 4 light circuit.

 

[Jimmyb]

No it doesnt make a difference. try null'in your test leads again.

 

[telectrix]

no, because R1+R2 is across L and E, whereas the lamps are across L and N.

 

[Silly Sausage]

Oooh, are you sure Jimmy?

Depends on how you're measuring it.
If you're putting a link between the earth bar and the protective device and measuring at the light you'll be picking up a parallel path through the lamp and Neutral to Earth/Neutral connection on a TNCS or all the way back to the supply transformer on TNS along the Neutral & Earth.

So you'll get a lower measurement.

Try drawing it.

 

[Deleted member 9648]

I normally disconnect the circuit totally and join L-E in a block.....going round removing lamps is a faff I can do without.

 

[telectrix]

agree with wirepuller. a lot less effort to dis circuit at CU than pulling out all lamps.

 

[malcolmsanford]

That is though lads if you find the right earth that goes with the right Line ................not always easy in a 32 way TP+N+E DB.

On an initial verification you would do your R1 + R2 before you connected to the board, but on a PIR it may be a little different.

 

[ipf]

That is though lads if you find the right earth that goes with the right Line ................not always easy in a 32 way TP+N+E DB.

On an initial verification you would do your R1 + R2 before you connected to the board, but on a PIR it may be a little different.

Along the TP+N+E DB lines, I have a PIR ongoing with 80-100 high bay lights in a warehouse to test. Wondering how many ccts fittings to test etc

ps should I post a new thread in ' Testing. Inspections'

 

[malcolmsanford]

Along the TP+N+E DB lines, I have a PIR ongoing with 80-100 high bay lights in a warehouse to test. Wondering how many ccts fittings to test etc

ps should I post a new thread in ' Testing. Inspections'

There are a few factors to this

1 Age of Installation
2. Type of environment
3 Condition of the installation
4 Any previous testing done
5 If any previous testing done what was the results and when was it done.

Obviously a 5 yr old installation is likely not to need as much sampling as a 40 yr old installation that as never been tested, but inversely a poor 5 yr old installation may need more sampling that an excellent 40 yr old one, it is really you judgement and experience when doing a visual inspection at the beginning before you quote for the job.

In PIR work all the training and book study is really a poor second to experience as an experience electrician will within a few hours have a fairly good take on how much work and sampling is going to be needed.

 

[Deleted member 26818]

That is though lads if you find the right earth that goes with the right Line ................not always easy in a 32 way TP+N+E DB.

On an initial verification you would do your R1 + R2 before you connected to the board, but on a PIR it may be a little different.

Which is exactly why I don't bother with R1 + R2 on a PIR, just Zs.

 

[SW1970]

Spin - what do you document as a reason for the LIM in this case? Thanks.

 

[Deleted member 26818]

Spin - what do you document as a reason for the LIM in this case? Thanks.

It's not a limitation, as you are not required to record R1 + R2 on a PIR, just to confirm continuity and polarity of conductors.
Obviously you also need to confirm that the Zs are low enough fro the CPD to operate.

 

[ipf]

Thanks Malcolm, I had my few hours assessing the general installation and decided that, in general, a vast majority of the db's (15 of) needed full test and inspection. It,s just a question of the lighting. The storage warehouse is an old 2nd world war munitions factory, no previous test details. It was used previously as some kind of engineering works, with db's added at over the years for various equipment added. Looking at the original lighting system, it is a joy to behold, obviously being designed to a very high spec, and takes me back to my apprenticeship days. However many of the lights are no longer in use or not operating, I would imagine, due to age. So it's a case of time, sorting out an old 10 way db and 30 gang switch system.
What a building though. More steel than the Forth bridge.

 

[malcolmsanford]

Sounds like as we would say a pension job, could be there forever.

Obviously the non working lights will come under remedial works and quoted separately from the PIR.

Basically all I would do on a PIR for Hi-bay lighting is IR between L-N to Earth, R2 with a wander lead and Zs at the grid switch.

 

[ipf]

Another week testing. About 150 sq yds, so not massive but double the amount of re-enforcement. took a local builder a week to knock through the outer wall fitting a door. Loads of ccts no longer in use so just disconnecting to remove at source. A lot of damage to various isolators throughout due to dumb stacker truck drivers, etc. May be a point with bonding regarding an external liquid gas supply tank ,still to check. Quite a few damaged overhead crane busbars, all supplies to be removed bar one. That may be a problem.